1. Field of the Invention
The present invention relates to a liquid crystal display device, and particularly to a double-sided liquid crystal display device and a backlight module thereof.
2. Description of the Related Art
With the progress of liquid crystal display techniques and the liquid crystal display devices have the advantages of light in weight and small in size, the liquid crystal display devices have been widely used in many kinds of electronic products, such as digital camera, personal digital assistant (PDA), mobile phone, notebook computer, thin-type flat panel television, and etc. The liquid crystal display device includes a liquid crystal display panel and a backlight module, wherein the backlight module is for providing plane light source to the liquid crystal display panel. Moreover, in order to satisfy different requirements, a double-sided liquid crystal display device, which is capable of displaying two frames at the same time, has been developed.
FIG. 1 is a schematic view of a conventional double-sided liquid crystal display device. Referring to FIG. 1, the conventional double-sided liquid crystal display device 100 is composed of two back-to-back liquid crystal display devices 110. Each of the liquid crystal display devices 110 includes a liquid crystal display panel 112 and a backlight module 114. The backlight module 114 includes a reflection plate 114a and a plurality of cold cathode fluorescent lamps (CCFLs) 114b. The cold cathode fluorescent lamp 114b are for providing light to the liquid crystal display panel 112, while the reflection plate 114a is for reflecting the light to the liquid crystal display panel 112.
The fact that the conventional double-sided liquid crystal display device 100 is composed of two back-to-back liquid crystal display devices 110 makes the liquid crystal display device 100 have a thick thickness. More concretely, in each of the liquid crystal display devices 110, a distance between the center of the cold cathode fluorescent lamp 114b and the reflection plate 114a is D1, a distance between the center of the cold cathode fluorescent lamp 114b and the liquid crystal display panel 112 is D2, the thickness of the reflection plate 114a is D4, the thickness of the liquid crystal display panel 112 is D5, and a distance between the two reflection plates 114a is D3. Therefore, the thickness of the conventional double-sided liquid crystal display device 100 is 2*(D1+D2+D4+D5)+D3.
FIG. 2 is a schematic view of another conventional double-sided liquid crystal display device. Referring to FIG. 2, in order to satisfy the thin-type requirement in electronic products, the conventional art provides another double-sided liquid crystal display device 100′, which includes two liquid crystal display panels 112 and a backlight module 120 disposed between the liquid crystal display panels 112. The backlight module 120 includes a reflection plate 122, a plurality of cold cathode fluorescent lamps 124 and a plurality of cold cathode fluorescent lamps 126, wherein the cold cathode fluorescent lamps 124 and 126 are disposed at two opposite sides of the reflection plate 122.
A distance between the center of the cold cathode fluorescent lamp 124/126 and the reflection plate 122 is D1, a distance between the center of the cold cathode fluorescent lamp 124/126 and the liquid crystal display panel 112 is D2, the thickness of the reflection plate 122 is D4, and the thickness of the liquid crystal display panel 112 is D5. Therefore, the thickness of the double-sided liquid crystal display device 100′ is 2*(D1+D2+D5)+D4. As compared to the double-sided liquid crystal display device 100, the double-sided liquid crystal display device 100′ decreases a thickness of D4+D3.
The reason for the thickness decrease of the conventional double-sided liquid crystal display device 100′ is uniting two backlight modules together to form a single piece. Therefore, if a backlight module with thinner thickness is provided, the thickness of the double-sided liquid crystal display device may further be decreased, which strengthens market competitiveness of the double-sided liquid crystal display device.